1. Field of the Invention
This invention pertains to improvements in swivel heads for borehole mining tools and particularly to a swivel head for a dual conduit tool string wherein the outer conduit is driven by the power swivel during drilling and mining while drilling or mining fluid is supplied to the annulus between the conduits or through the center conduit.
2. Description of the Prior Art
U.S. Pat. No. 4,077,671 issued to P. R. Bunnelle on Mar. 7, 1978 discloses a separate drilling (FIG. 2) and a mining head (FIG. 6) wherein the heads are alternated each time the function of the tool is changed. The swivel joint is axial with respect to the drill string in each head. The second below the axial swivel joint is driven by the torque wrench during mining.